Camshaft adjusting device

ABSTRACT

A camshaft adjusting device having a vane-type adjuster, which includes a stator which is rotatably drivable by a crankshaft; and a rotor which is rotatably supported in the stator and is connectable to a camshaft, a plurality of radially inwardly projecting projections, which divide an annular space between the stator and the rotor into multiple pressure chambers, being provided on the stator; and a plurality of radially outwardly projecting vanes, which divide the pressure chambers into oppositely acting working chambers, being provided on the rotor; a pressure medium being applicable to the working chambers to optionally adjust the rotor with respect to the stator via a central valve, the central valve being integrally connected to the rotor or to the stator or to a component which is rotatably fixedly connected to one of the two parts.

This claims the benefit of German Patent Application DE102013209930.4, filed May 28, 2013 and hereby incorporated by reference herein.

The present invention relates to a camshaft adjusting device.

BACKGROUND

Camshaft adjusting devices include a camshaft and a vane-type adjuster which, in its basic configuration, has a stator which is drivable by a crankshaft and a rotor which is rotatably fixedly connected to the camshaft. An annular space is provided between the stator and the rotor, which is divided into a plurality of pressure chambers by projections which are rotatably fixedly connected to the stator and project radially to the inside, the pressure chambers each being divided into two working chambers having different directions of action by a vane which projects radially to the outside from the rotor. Depending on the application of a pressure medium to the working chambers, the rotor is then adjusted with respect to the stator, and the camshaft is adjusted with respect to the crankshaft, in the “advance” or “retard” direction. The working chambers are delimited by the side surfaces of the projections and the vanes and by a first sealing surface on the rotor and a second sealing surface on the stator, against which the projections and the vanes rest by their front surfaces, forming a seal.

To apply pressure to the working chambers, for example a central valve having a movable valve body may be provided, which has a plurality of control edges and pressure medium channels through which the pressure medium may be optionally introduced into the working chambers as a function of the position of the valve body. The central valve is furthermore used to clamp the rotor to the camshaft by the fact that, on the outside, the central valve rests against an external side surface with the aid of a radial flange and is screwed into a female thread of the camshaft with the aid of a threaded section. A frictionally engaged connection between the camshaft and the rotor, and between the rotor and the central valve, is thus formed, by means of which the adjusting forces necessary for the adjusting movement of the camshaft are transmitted. In this specific embodiment, the central valve is also referred to as the central screw.

One disadvantage of this approach is the fact that the manufacture of the threads raises costs, and a certain installation space for the threads must also be provided on the camshaft and the central valve. Moreover, the threads and the press-fit connections between the rotor and the central screw, and between the rotor and the camshaft, require adequate material cross sections as well as low component tolerances to achieve the desired contact pressures.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a camshaft adjusting device, in which the central valve is fastened as cost-effectively as possible, avoiding the aforementioned disadvantages.

The present invention provides a camshaft adjusting device having a vane-type adjuster which includes a stator which is rotatably drivable by a crankshaft; and a rotor which is rotatably supported in the stator and is connectable to a camshaft, a plurality of radially inwardly projecting projections, which divide an annular space between the stator and the rotor into multiple pressure chambers, being provided on the stator; and a plurality of radially outwardly projecting vanes, which divide the pressure chambers into oppositely acting working chambers, being provided on the rotor; a pressure medium being applicable to the working chambers to optionally adjust the rotor with respect to the stator via a central valve. The central valve is integrally connected to the rotor or to the stator or to a component which is rotatably fixedly connected to one of the two parts.

The advantage of the proposed approach may be seen in the fact that the central valve and the other component for fastening the central valve do not need to be machined separately. Moreover, the integral connection results in a very strong connection which requires very little installation space. The components to be connected are melted on locally and connected to each other, it being possible to supply additional material to create the integral connection. Furthermore, integral connections may be manufactured with high dimensional accuracy, fully automatically and cost-effectively in mass production using modern manufacturing methods.

The integral connection may preferably be formed by a welded connection. Welded connections are a particularly strong type of integral connection, in which the two components are melted on locally and are integrally connected to each other by a coalescence of the material. The integral connection may be further strengthened by supplying additional melted-on welding material in a locally targeted manner, the components to be connected being simultaneously melted onto the surfaces by the very hot, melted-on welding material. In particular, laser welding methods, with the aid of which the material may be locally and very accurately heated to a very high temperature, may be used as modern welding methods.

It is furthermore proposed that the central valve may be integrally connected to a cover of the stator. The proposed connection is advantageous from a manufacturing perspective, since the cover is very easily accessible from the outside so that the central valve may be connected to the camshaft adjusting device on an outer surface. The location of the integral connection is also positioned at a point on the central valve which is not part of the function surfaces, so that these function surfaces are not disadvantageously influenced, i.e., in terms of their dimensional accuracy, by the manufacture of the integral connection.

It is furthermore proposed that the central valve may have a radial flange situated on a front side, which projects radially to the outside. Due to the proposed radial flange, a type of stop may be created, with the aid of which the assembly of the camshaft adjusting device is simplified. In particular, the insertion depth of the central valve into a tubular end section of the camshaft may be limited thereby.

The central valve may furthermore be integrally connected to the sealing cover in a radially outer section of the radial flange. For practical purposes, the radial flange forms a protruding wall section, which may be used to fasten the central valve. It is particularly advantageous that the integral connection may thereby be situated at a greater distance to the function surfaces of the central valve, so that the temperatures in the central valve which occur in the area of the function surfaces are lower during the creation of the integral connection.

It is furthermore proposed that the radial flange may be dimensioned in such a way that it overlaps the side surface of the rotor. Due to the proposed dimensioning of the radial flange, an additional stop is created for limiting the insertion movement of the central valve into the through-opening.

It is furthermore proposed that the rotor may have a central through-opening in which the central valve is situated. The through opening in the rotor is advantageous for indirectly or directly fixing the central valve in place with respect to the rotor during the fastening operation.

In particular, the central valve may be integrally connected to the stator or to a component which is rotatably fixedly connected to the stator, and the camshaft may be integrally connected to the rotor or to a component which is rotatably fixedly connected to the rotor. The connection between the camshaft and the rotor as well as the connection between the stator and the central valve thus both have an integral design. The rotor in this case is particularly rotatably fixedly connected to the camshaft by the indirect or direct integral connection thereto.

It is furthermore proposed that the camshaft may have a tubular end section, by means of which it extends into the through-opening between the rotor and the central valve, and elongated openings extending in the circumferential direction are provided in the tubular end section, through which the pressure medium may be introduced from the central valve into the working chambers. Due to the connection of the central valve to the cover of the stator and the connection of the camshaft to the rotor, the tubular end section executes a relative movement with respect to the central valve fastened to the cover of the stator when the camshaft is adjusted. Since the central valve is situated in the tubular end section of the camshaft, and an inflow and outflow of the pressure medium via the central valve must be possible at the same time, the proposed elongated openings extending in the circumferential direction are provided in the tubular end section, these elongated openings permitting an inflow and outflow of the pressure medium through the tubular end section of the camshaft over a certain angle range of the adjusting movement.

BRIEF DESCRIPTION OF THE DRAWING

The present invention is explained in greater detail below on the basis of one preferred exemplary embodiment.

FIG. 1 shows a sectional representation of a camshaft adjusting device according to the present invention.

DETAILED DESCRIPTION

A sectional representation of a camshaft adjusting device having a vane-type adjuster which includes a rotor 1 and a stator 2 is apparent in FIG. 1. Stator 2 includes a driving surface, such as a toothing, radially on the outside, with the aid of which the valve-type adjuster is driven by an endless traction means or device during operation. The driving action may be carried out by a crankshaft or another drive shaft of an internal combustion engine. Stator 2 itself has an annular design and includes a plurality of projections 13 which project radially to the inside, in which a fastening opening 14 is provided for screwing two covers 3 and 4 which cover stator 2 at the side. If stator 2 has a cup-shaped design, only cover 3 is provided, which covers cup-shaped stator 2 at the side. Covers 3 and 4 and stator 2 form a rotatably fixed assembly, due to the screw connection. Projections 13 projecting radially to the inside extend up to a first sealing surface of rotor 1 and thereby divide an annular space present between rotor 1 and stator 2 into multiple pressure chambers. A plurality of vanes is furthermore provided on rotor 1, which extend up to a second sealing surface of stator 2 and thereby further divide the created pressure chambers into two oppositely acting working chambers. A pressure medium may be optionally applied to each working chamber through a pressure medium line via a central pressure medium circuit. To rotate rotor 1 with respect to stator 2, a pressure medium is applied to the working chambers of a first direction of action on one side of the vanes, while the pressure medium from the working chambers of a second direction of action is fed back into a pressure medium reservoir on the other side of the vanes. By applying the pressure medium to the working chambers, rotor 1 is rotated with respect to stator 2 either in the direction of rotation of stator 2 or counter to the direction of rotation of stator 2. Since stator 2 is rotatably fixedly connected to the crankshaft via the endless traction means, and rotor 1 is rotatably fixedly connected to a camshaft 5, the rotation angle of camshaft 5 to the crankshaft is also adjusted. To this extent, the vane-type adjuster corresponds to the prior art.

Rotor 1 has a central through-opening 11, into which camshaft 5 extends via a tubular end section 9. Elongated openings 12, which are oriented in the circumferential direction, are provided on tubular end section 9 of camshaft 5. Camshaft 5 is rotatably fixedly connected to rotor 1 via tubular end section 9, e.g., via one or multiple welded connections, an adhesive connection, a threaded connection or a press-fit connection.

A central valve 6 is furthermore provided, which has multiple through-openings 15 and a central cylindrical recess, in which a spring-loaded valve body 7 is movably guided, which has different control edges and through bore-holes. Central valve 6 also has a radial flange 8 on its front side, which projects radially to the outside and has a larger outer diameter than the inner diameter of through-opening 11 of rotor 1, so that radial flange 8 covers both the front side of end section 9 of camshaft 5 and a partial section of the side surface of rotor 1. Central valve 6 is situated in tubular end section 9 of camshaft 5 and is integrally connected to cover 3 of stator 2 on the radial outside of radial flange 8, via a welded connection 10.

Welded connection 10 may be a circumferential, uninterrupted weld seam, which is implemented, for example, with the aid of a highly dimensionally accurate laser welded connection. The proposed arrangement of welded connection 10 on the radial outside of radial flange 8 is useful to the extent that it thereby has the largest possible distance to the valve surfaces of central valve 6 between central valve 6 and tubular end section 9 or between valve body 7 and the cylindrical inner wall of central valve 6, so that the amount of heat introduced into the valve surfaces of central valve 6 during welding is lower. Due to the overlapping between the front side of tubular end section 9 and the side surface of rotor 1 implemented by the larger outer diameter, radial flange 8 furthermore provides a stop which limits the insertion movement of central valve 6 into through-opening 11 of rotor 1 or into tubular end section 9 of camshaft 5, which may simplify assembly.

In the illustrated specific embodiment of the present invention, central valve 6 is integrally connected to cover 3 of stator 2, and camshaft 5 is connected to rotor 1, via tubular end section 9. When rotor 1 is adjusted with respect to stator 2, rotor 1, together with camshaft 5 and tubular end section 9, executes a rotary motion with respect to central valve 6 fixedly attached to the stator. Due to elongated openings 12 oriented in the circumferential direction, the pressure medium may flow out of or into the working chambers via through-openings 15 of central valve 6 in the different angular positions of rotor 1.

The proposed integral connection between central valve 6 and cover 3 is thus advantageous, since no special preceding machining steps for the components are needed to create this connection, so that the manufacturing costs may be reduced. Moreover, the integral connection may be implemented in a very small installation space in a noticeably space-saving manner, since the integral connection is very strong in and of itself, and, to create the connection, only smaller surfaces which are freely accessible from the outside must be present on the components to be connected.

In the present exemplary embodiment, the connection was described on the basis of an integral connection between central valve 6 and cover 3. In another assignment of the components, however, central valve 6 may also be integrally connected directly to stator 2 or rotor 1 and have the same advantages.

However, the described fastening of central valve 6 to cover 3 is particularly advantageous, since central valve 6, which includes provided radial flange 8, and cover 3 form surfaces which are particularly easily accessible from the outside, on which the integral connection may be provided. Furthermore, the described assignment results in a particularly simple configuration of the camshaft adjusting device having two assemblies, namely a first assembly including cover 3 or stator 2 and rotatably fixedly connected central valve 6, and a second assembly including rotor 1 and camshaft 5 connected via the tubular end section.

Cover 3 may also be integrally connected to central valve 6 in a separate, preceding operation and then fastened to stator 2, together with central valve 6, as an assembly, it being advantageously possible for rotor 1 to already be connected to camshaft 5 during this operation. Cover 3, together with central valve 6 fastened thereto, is then inserted into tubular end section 9 of camshaft 5 and screwed to opposite cover 4 through fastening openings 14, via appropriate fastening screws.

LIST OF REFERENCE NUMERALS

1 Rotor

2 Stator

3 Cover

4 Cover

5 Camshaft

6 Central valve

7 Valve body

8 Radial flange

9 End section

10 Welded connection

11 Through-opening

12 Elongated openings

13 Projection

14 Fastening opening

15 Through-opening 

What is claimed is:
 1. A camshaft adjusting device having a vane adjuster, the camshaft adjusting device comprising: a stator rotatably drivable by a crankshaft; a rotor rotatably supported in the stator and connectable to a camshaft; a plurality of radially inwardly projecting projections dividing an annular space between the stator and the rotor into multiple pressure chambers and being provided on the stator; a plurality of radially outwardly projecting vanes dividing the pressure chambers into oppositely acting working chambers and being provided on the rotor; a pressure medium being applicable to the working chambers to selectively adjust the rotor with respect to the stator via a central valve, the central valve being integrally connected to the rotor or to the stator or to a component connected in a rotationally fixed manner to the rotor or the stator.
 2. The camshaft adjusting device as recited in claim 1 wherein the integral connection is a welded connection.
 3. The camshaft adjusting device as recited in claim 1 wherein the component is a cover of the stator and the central valve is integrally connected to the cover of the stator.
 4. The camshaft adjusting device as recited in claim 3 wherein the central valve has a radially outwardly projecting radial flange situated on a front side.
 5. The camshaft adjusting device as recited in claim 4 wherein the central valve is integrally connected to the sealing cover in a radially outer section of the radial flange.
 6. The camshaft adjusting device as recited in claim 4 wherein the radial flange is dimensioned to overlap a side surface of the rotor.
 7. The camshaft adjusting device as recited in claim 1 wherein the rotor has a central through-opening, the central valve being situated in the central through-opening.
 8. The camshaft adjusting device as recited in claim 1 wherein the central valve is integrally connected to the stator or to the component, the component being rotatably fixedly connected to the stator, the camshaft being integrally connected to the rotor or to a further component rotatably fixedly connected to the rotor.
 9. The camshaft adjusting device as recited in claim 7 wherein the camshaft has a tubular end section extending into the through-opening between the rotor and the central valve, the tubular end section having elongated openings, the pressure medium conducted from the central valve via the elongated opening into the working chambers.
 10. The camshaft adjusting device as recited in claim 9 wherein the central valve is integrally connected to the stator or to the component, the component being rotatably fixedly connected to the stator, the camshaft being integrally connected to the rotor or to a further component rotatably fixedly connected to the rotor. 